Mainz 2017 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 19: Precision Measurements and Metrology: Interferometry II (with Q)
A 19.8: Vortrag
Dienstag, 7. März 2017, 16:15–16:30, P 104
Random bosonic states for robust quantum metrology — Michał Oszmaniec1, Remigiusz Augusiak1,2, •Christian Gogolin1,3, Janek Kołodyński1, Antonio Acín1,4, and Maciej Lewenstein1,4 — 1ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain — 2Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland — 3Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany — 4ICREA-Institució Catalana de Recerca i Estudis Avançats, Lluis Companys 23, 08010 Barcelona, Spain
We study how useful random states are for quantum metrology, i.e., whether they surpass the classical limits imposed on precision in the canonical phase estimation scenario. We prove that random pure states drawn from the Hilbert space of distinguishable particles typically do not lead to super-classical scaling of precision. Conversely, we show that random states from the symmetric subspace typically achieve the optimal Heisenberg scaling. Surprisingly, the Heisenberg scaling is observed for states of arbitrarily low purity and preserved under the loss of fixed number of particles. Moreover, we prove that for such states a standard photon-counting interferometric measurement suffices to typically achieve the Heisenberg scaling of precision for all values of the phase at the same time. Finally, we demonstrate that metrologically useful states can be prepared with short random optical circuits.